"They felt intimidated and were disorientated by the noise and crowd," she told The New Paper on Tuesday.

Madam Aun declined to go into details of the incident as police investigations are ongoing.

But a 17-minute video posted on YouTube on Sunday shows the protesters approaching the stage where the Y-Stars, who are people with Down syndrome and other intellectual disabilities, were just about to start their performance.

Mr Ngerng and Ms Han, who had microphones, could be heard shouting slogans such as "Return our CPF!"

The protesters also heckled the Minister of State for Trade and Industry, Mr Teo Ser Luck, who was the guest of honour for the YMCA event.

They left after the Y-Stars started performing but returned later after another group of performers, the YMCA Deaf Generation, took to the stage.

Mr Johnson Chia, 22, co-leader of YMCA Youth Deaf Generation, said: "I felt so worried for our deaf members and the actual performance as the protest was so loud that it affected our tempo and beat. (But) we continued as we needed to deliver our best performance in front of the audience. We all did our best working and playing together."

Miss Rachel Koh, 23, the other co-leader, was angry at the "inconsideration and lack of manners" of the protesters.

She said: "There were people watching our performance and we could not allow other things to distract us for the sake of the audience to enjoy the music. Some rhythms were off because of the interruption."

Ms Lily Goh, director and founder of ExtraOrdinary Horizons (Deaf Singapore), was also concerned about the well-being of the performers.

"Luckily, they were not badly affected as they have good teamwork," she said.

"However, think of other people with disabilities, including children with special needs. They were indeed shocked and they needed a longer time to recover."

SADDENNED

Madam Aun, an active parent volunteer for over 20 years, said the parents were saddened by the turn of events.

"The performers have varying abilities and it took them between nine months and a year to learn the dance," she said.

"We are like a support group. The mothers and caregivers meet at our studio at Goodman Arts Centre as their children practise for about two hours every Saturday.

"We are not angry but it's definitely disappointing."

Madam Aun, 55, had previously told The Straits Times that the group and their parents would decline to meet Mr Ngerng after he wrote on his blog on Sunday that he hoped to meet them to apologise.

He wrote: "YMCA might have been retooled for a political purpose at the protest but there are good people at the YMCA, as we have (sic) seen among the volunteers and attendees at the event yesterday."

His supporters have also started a petition, accusing YMCA Singapore of "using children with special needs as human shields" for political reasons.

Madam Aun told TNP: "If he wants to apologise, it's fine, but we don't see the need to meet."

The Y-Stars performers will not be deterred by this episode, she added.

"There will be another chance to perform."

"I felt so worried for our deaf members and the actual performance as the protest was so loud that it affected our tempo and beat."

- Mr Johnson Chia, 22, co-leader of YMCA Youth Deaf Generation

How best to share public space?

TNP INFOGRAPHICS: LEE HUP KHENG

The Speakers' Corner should be reserved for protests and demonstrations, said Mr Gilbert Goh, a volunteer at non-profit society transitioning.org.

On Sept 27, NParks allowed YMCA's concert and a protest by #ReturnOurCPF group to go ahead at Hong Lim Park.

Mr Goh, who has organised several large rallies there, said: "We have no alternative site like public non-government organisations have."

Speakers' Corner, set up in Hong Lim Park in 2000, is Singapore's only outdoor venue where the locals are allowed to give public speeches without a Public Entertainment Licence. In 2004, it was expanded to allow performances and exhibitions if the organiser and participants are Singaporeans.

Not everyone agrees with Mr Goh.

Civil rights group Maruah president Braema Mathi said the Speakers' Corner is a space that is "used and valued" by civil society groups, but other groups should be welcome to use it as well.

But organisers should be mindful of holding events at Hong Lim Park especially when they have vulnerable participants. She said NParks can facilitate in negotiations on sharing the space.

Singapore Management University Law Professor Eugene Tan said: "The Speakers' Corner was created as a space for people to express and share their views on a variety of issues, not just politics alone. We would be poorer for it, if we restrict the type or number of use for the space.

"It would be worse if Hong Lim Park becomes like some online spaces - echo chambers in which purposeful engagement is avoided, closed minds preferred and polarised views generated."

So should rules be tightened to prevent a similar incident from recurring?

Management of Speaker's Corner was transferred from the police to NParks in 2008. An online registration system replaced permit applications at the Kreta Ayer Neighbourhood Police Post.

Should permits be handled by the police again?

Worker's Party (WP) member and Non-Constituency Member of Parliament Yee Jenn Jong said he did not favour more rules for Speakers' Corner.

On his Facebook page, he called the actions of the protesters "inappropriate" and added: "Some want to use the space for protests and some want to use it to celebrate. We need not be so prescriptive about what the space can be used for."

MORE SPACES

What about WP chairman Sylvia Lim's proposal in July to open up more spaces for protests like designated roads?

In an online poll by The New Paper, 80 per cent of the 900 respondents did not think that protests and marches should go beyond Hong Lim Park.

When TNP contacted Ms Lim and party spokesman Gerald Giam, the latter said the party would not comment.

Then should Hong Lim Park be limited to just one event a day?

YMCA applied to NParks in April to use Hong Lim Park on Sept 27 and received approval on Sept 9. Blogger Han Hui Hui's online application on Sept 22 to use the same venue for "Return Our CPF" was approved the same day.

An NParks' spokesman said multiple events held on the same date at Hong Lim Park previously had no issues.

The spokesman added: "No adverse or disorderly incidents have ever ensued in these previous events because the groups showed consideration and respect for each other."

"It would be worse if Hong Lim Park becomes like some online spaces - echo chambers in which purposeful engagement is avoided, closed minds preferred and polarised views generated."

- Singapore Management University Law Professor Eugene Tan

REACTIONS ONLINE

I am appalled at the behaviour of Roy Ngerng, Han Hui Hui and their supporters who marched right into a charity event where special needs children, disabled children and the elderly were present.

And for those who might be wondering, I also find it questionable to heckle a minister during a charity event where he is guest of honour.

But let's get one thing right - Roy and company did not heckle the children. This is quite clear from the videos that have emerged online.

Mr Andrew Loh, The Online Citizen

The chosen name of "Singapore's Speakers' Corner" suggests to most of us that it is a place where people assemble and congregate to give speeches rather than for social or entertainment purposes.

Of course, YMCA has done nothing wrong when it held its YMCA Proms @ the Park on Saturday, Sept 27, but why fight over a tiny turf with other smaller participants?

YMCA is a big and well-established organisation and therefore can well afford to hold its activities in a commercial building.

Netizen Joseph Chan

You can blame the park, blame the Government, blame anything and anyone, but what we've all witnessed today is utter disrespect and lack of civility from the CPF protesters.

You may have a valid point or two in your cause, but if you're going to act exactly the same way as you do online - shouting, bitching, cursing and being little spoilt kids, don't expect anyone to take you seriously.

Is this truly what you call being Singaporean? Be adults. Be civilised.